Addition of low sodium does not increase sensitivity to glucose in wild-type mice, or lead to partial glucose taste detection in T1R3 knock-out mice.

The sodium glucose cotransporter 1 (SGLT1) has been proposed as a non-T1R glucosensor contributing to glucose taste. Studies have shown that the addition of NaCl at very weak concentrations to a glucose stimulus can enhance signaling in the gustatory nerves of mice and significantly lower glucose detection thresholds in humans. Here, we trained mice with (wild-type; WT) and without (knockout; KO) a functioning T1R3 subunit on a two-response operant detection task to differentially respond to the presence or absence of a taste stimulus immediately after sampling. After extensive training (∼40 sessions), KO mice were unable to reliably discriminate 2 M glucose+0.01 M NaCl from 0.01 M NaCl alone, but all WT mice could. We then tested WT mice on a descending array of glucose concentrations (2.0-0.03 M) with the addition of 0.01 M NaCl vs. 0.01 M NaCl alone. The concentration series was then repeated with glucose alone vs. water. We found no psychophysical evidence of a non-T1R taste transduction pathway involved in the detection of glucose. The addition of NaCl to glucose did not lower taste detection thresholds in WT mice, nor did it render the stimulus detectable to KO mice, even at 2 M. The proposed pathway must contribute to functions other than sensory-discriminative detection, at least when tested under these conditions. Detection thresholds were also derived for fructose and found to be 1/3 log10 lower than for glucose, but highly correlated (r = 0.88) between the two sugars, suggesting that sensitivity to these stimuli in this task was based on a similar neural process.

Enhanced azadirachtin production in neem (Azadirachta indica) callus through NaCl elicitation: Insights into differential protein regulation via shotgun proteomics.

With their remarkable bioactivity and evolving commercial importance, plant secondary metabolites (PSMs) have gained significant research interest in recent years. Plant tissue culture serves as a credible tool to examine how abiotic stresses modulate the production of PSMs, enabling clear insights into plant stress responses and the prospects for controlled synthesis of bioactive compounds. Azadirachta indica, or neem has been recognized as a repository of secondary metabolites for centuries, particularly for the compound named azadirachtin, due to its bio-pesticidal and high antioxidant properties. Introducing salt stress as an elicitor makes it possible to enhance the synthesis of secondary metabolites, specifically azadirachtin. Thus, in this research, in vitro callus cultures of neem were micro-propagated and induced with salinity stress to explore their effects on the production of azadirachtin and identify potential proteins associated with salinity stress through comparative shotgun proteomics (LCMS/MS). To induce salinity stress, 2-month-old calli were subjected to various concentrations of NaCl (0.05-1.5%) for 4 weeks. The results showed that the callus cultures were able to adapt and survive in the salinity treatments, but displayed a reduction in fresh weight as the NaCl concentration increased. Notably, azadirachtin production was significantly enhanced in the salinity treatment compared to control, where 1.5% NaCl-treated calli produced the highest azadirachtin amount (10.847 ± 0.037 mg/g DW). The proteomics analysis showed that key proteins related to primary metabolism, such as defence, energy, cell structure, redox, transcriptional and photosynthesis, were predominantly differentially regulated (36 upregulated and 93 downregulated). While a few proteins were identified as being regulated in secondary metabolism, they were not directly involved in the synthesis of azadirachtin. In conjunction with azadirachtin elicitation, salinity stress treatment could therefore be successfully applied in commercial settings for the controlled synthesis of azadirachtin and other plant-based compounds. Further complementary omics approaches can be employed to enhance molecular-level modifications, to facilitate large-scale production of bioactive compounds in the future.

Halopriming in the submergence-tolerant rice variety improved the resilience to salinity and combined salinity-submergence at the seedling stage.

The role of halopriming in alleviating the detrimental effects of salinity and combined salinity-submergence was evaluated using two rice genotypes, "IR06F148" (anaerobic germination + submergence tolerant [Sub1]) and "Salt-star" (salt tolerant) with contrasting levels of tolerance. Nonprimed seeds and those primed with 1% calcium chloride (CaCl2) were germinated, and the seedlings were exposed to salinity (50 or 100 mM sodium chloride [NaCl]) and submergence (nonsaline or saline water). Salinity substantially inhibited plant height, shoot/root dry mass, and leaf area. Priming improved the resilience to 50 mM NaCl by increasing the chlorophyll content and lowering hydrogen peroxide (H2O2) production; and to 100 mM NaCl by increasing the total soluble sugars. However, apparent differences in the responses of primed "Salt-star", such as an increase in the Na+, K+, and Ca2+ levels, indicated that halopriming differentially affected the response to salt based on the salinity tolerance of the variety. Submergence reduced the shoot biomass, chlorophyll, and photosynthetic efficiency to a greater extent in "Salt-star" than in "IR06F148". Priming, especially in "Salt-star", caused a lesser reduction in the chlorophyll (Chl) and maximum quantum yield of photosystem II (Fv/Fm) but increased the total soluble sugars post-submergence, indicating a boost in the photosynthetic efficiency. The responses of the two varieties to submergence depended on their tolerance, and halopriming affected each variety differently. The metabolic and molecular changes induced by halopriming in submergence-tolerant rice may be explored further to understand the underlying mechanisms of improved resilience.

Brain sodium sensing for regulation of thirst, salt appetite, and blood pressure.

The brain possesses intricate mechanisms for monitoring sodium (Na) levels in body fluids. During prolonged dehydration, the brain detects variations in body fluids and produces sensations of thirst and aversions to salty tastes. At the core of these processes Nax , the brain's Na sensor, exists. Specialized neural nuclei, namely the subfornical organ (SFO) and organum vasculosum of the lamina terminalis (OVLT), which lack the blood-brain barrier, play pivotal roles. Within the glia enveloping the neurons in these regions, Nax collaborates with Na+ /K+ -ATPase and glycolytic enzymes to drive glycolysis in response to elevated Na levels. Lactate released from these glia cells activates nearby inhibitory neurons. The SFO hosts distinct types of angiotensin II-sensitive neurons encoding thirst and salt appetite, respectively. During dehydration, Nax -activated inhibitory neurons suppress salt-appetite neuron's activity, whereas salt deficiency reduces thirst neuron's activity through cholecystokinin. Prolonged dehydration increases the Na sensitivity of Nax via increased endothelin expression in the SFO. So far, patients with essential hypernatremia have been reported to lose thirst and antidiuretic hormone release due to Nax -targeting autoantibodies. Inflammation in the SFO underlies the symptoms. Furthermore, Nax activation in the OVLT, driven by Na retention, stimulates the sympathetic nervous system via acid-sensing ion channels, contributing to a blood pressure elevation.

Genome-wide systematic survey and analysis of the RNA helicase gene family and their response to abiotic stress in sweetpotato.

Sweetpotato (Ipomoea batatas (L.) Lam.) holds a crucial position as one of the staple foods globally, however, its yields are frequently impacted by environmental stresses. In the realm of plant evolution and the response to abiotic stress, the RNA helicase family assumes a significant role. Despite this importance, a comprehensive understanding of the RNA helicase gene family in sweetpotato has been lacking. Therefore, we conducted a comprehensive genome-wide analysis of the sweetpotato RNA helicase family, encompassing aspects such as chromosome distribution, promoter elements, and motif compositions. This study aims to shed light on the intricate mechanisms underlying the stress responses and evolutionary adaptations in sweetpotato, thereby facilitating the development of strategies for enhancing its resilience and productivity. 300 RNA helicase genes were identified in sweetpotato and categorized into three subfamilies, namely IbDEAD, IbDEAH and IbDExDH. The collinearity relationship between the sweetpotato RNA helicase gene and 8 related homologous genes from other species was explored, providing a reliable foundation for further study of the sweetpotato RNA helicase gene family's evolution. Furthermore, through RNA-Seq analysis and qRT-PCR verification, it was observed that the expression of eight RNA helicase genes exhibited significant responsiveness to four abiotic stresses (cold, drought, heat, and salt) across various tissues of ten different sweetpotato varieties. Sweetpotato transgenic lines overexpressing the RNA helicase gene IbDExDH96 were generated using A.rhizogenes-mediated technology. This approach allowed for the preliminary investigation of the role of sweetpotato RNA helicase genes in the response to cold stress. Notably, the promoters of RNA helicase genes contained numerous cis-acting elements associated with temperature, hormone, and light response, highlighting their crucial role in sweetpotato abiotic stress response.

Production, characterization and biomedical potential of biosurfactants produced by haloalkaliphilic archaea from Wadi El-Natrun, Egypt.

Extreme halophilic archaea that can live in high saline environments can offer potential applications in different biotechnological fields. This study delves into the fascinating field of halophilic archaea and their ability to produce biosurfactants. Some strains of haloarchaea were isolated from Wadi El-Natrun and were screened for biosurfactants production in a standard basal medium using emulsification index assay. Two strains were chosen as the potential strains for surface tension reduction. They were identified as Natrialba sp. BG1 and N3. The biosurfactants production was optimized and the produced emulsifiers were partially purified and identified using FTIR and NMR. Sequential statistical optimization, Plackett-Burman (PB) and Box-Behnken Designs (BBD) were carried out using 5 factors: oil, NaCl, casamino acids, pH, and inoculum size. The most significant factors were used for the next Response Surface Methodology experiment. The final optimal conditions for biosurfactants production were the inoculum size 2% pH 11 and NaCl 250 g/L, for Natrialba sp. BG1 and inoculum size 2.2%, pH 10 and NaCl 100 g/L for Natrialba sp. N3. The produced biosurfactants were tested for wound healing and the results indicated that Natrialba sp. BG1 biosurfactants is more efficient than Natrialba sp. N3 biosurfactants. Biosurfactants extracts were tested for their cytotoxic effects on normal cell line as well as on different cancer cells using MTT assay. The findings demonstrated that varying concentrations of the biosurfactants (31.25, 62.5, 125, 250, 500 and 1000 µg/mL) exhibited cytotoxic effects on the cell lines being tested. Additionally, the outcomes unveiled the presence of anti-inflammatory and antioxidant properties for both biosurfactants. Consequently, they could potentially serve as natural, safe, and efficient novel agents for combating cancer, promoting wound healing, and providing anti-inflammatory and antioxidant benefits.

Antioxidant production promotes defense mechanism and different gene expression level in Zea mays under abiotic stress.

The growth and productivity of maize are severely affected by soil salinity. The crucial determinants for the future performance of plants are productive for seed germination and seedling establishment; however, both stages are liable to soil salinity. For grain, maize is an economically significant crop sensitive to abiotic stresses. However, little is known about defense responses by the salinity-induced antioxidant and oxidative stress in maize. In our work, the commercially available maize variety Raka-Poshi was grown in pots for 30 days under greenhouse conditions. To evaluate the salt-induced oxidative/antioxidant responses in maize for salt stress 0, 25, 50, 75, 100 and 150 mM concentrations, treatments were provided using sodium chloride (NaCl). All the biochemical indices were calculated under all NaCl concentrations, while drought was induced by up to 50% irrigation water. After 30 days of seed germination, the maize leaves were collected for the measurement of lipid peroxidase or malondialdehyde (MDA), glutathione reductase (GR), guaiacol peroxidase (GPOD), hydrogen peroxide (H2O2), superoxide dismutase (SOD), lipoxygenase (LOX), catalase (CAT), ascorbate peroxidase (APOD) and glutathione-S-transferase (GST). The results revealed a 47% reduction under 150 mM NaCl and 50% drought stress conditions. The results have shown that the successive increase of NaCl concentrations and drought caused an increase in catalase production. With successive increase in NaCl concentration and drought stress, lower levels of H2O2, SOD, and MDA were detected in maize leaves. The results regarding the morphology of maize seedlings indicated a successive reduction in the root length and shoot length under applications of salt and drought stress, while root-to-shoot weights were found to be increased under drought stress and decreased under salt stress conditions During gene expression analysis collectively indicate that, under drought stress conditions, the expression levels of all nine mentioned enzyme-related genes were consistently downregulated.

Temporal dynamics of stress response in Halomonas elongata to NaCl shock: physiological, metabolomic, and transcriptomic insights.

BACKGROUND: The halophilic bacterium Halomonas elongata is an industrially important strain for ectoine production, with high value and intense research focus. While existing studies primarily delve into the adaptive mechanisms of this bacterium under fixed salt concentrations, there is a notable dearth of attention regarding its response to fluctuating saline environments. Consequently, the stress response of H. elongata to salt shock remains inadequately understood. RESULTS: This study investigated the stress response mechanism of H. elongata when exposed to NaCl shock at short- and long-time scales. Results showed that NaCl shock induced two major stresses, namely osmotic stress and oxidative stress. In response to the former, within the cell's tolerable range (1-8% NaCl shock), H. elongata urgently balanced the surging osmotic pressure by uptaking sodium and potassium ions and augmenting intracellular amino acid pools, particularly glutamate and glutamine. However, ectoine content started to increase until 20 min post-shock, rapidly becoming the dominant osmoprotectant, and reaching the maximum productivity (1450 ± 99 mg/L/h). Transcriptomic data also confirmed the delayed response in ectoine biosynthesis, and we speculate that this might be attributed to an intracellular energy crisis caused by NaCl shock. In response to oxidative stress, transcription factor cysB was significantly upregulated, positively regulating the sulfur metabolism and cysteine biosynthesis. Furthermore, the upregulation of the crucial peroxidase gene (HELO_RS18165) and the simultaneous enhancement of peroxidase (POD) and catalase (CAT) activities collectively constitute the antioxidant defense in H. elongata following shock. When exceeding the tolerance threshold of H. elongata (1-13% NaCl shock), the sustained compromised energy status, resulting from the pronounced inhibition of the respiratory chain and ATP synthase, may be a crucial factor leading to the stagnation of both cell growth and ectoine biosynthesis. CONCLUSIONS: This study conducted a comprehensive analysis of H. elongata's stress response to NaCl shock at multiple scales. It extends the understanding of stress response of halophilic bacteria to NaCl shock and provides promising theoretical insights to guide future improvements in optimizing industrial ectoine production.

Exogenous application of mycotoxin fusaric acid improve the morphological, cytogenetic, biochemical and anatomical parameters in salt (NaCl) stressed Allium cepa L.

Salinity is one of the most important abiotic stress factors that negatively affect plant growth and development. In contrast, fusaric acid (FA), a mycotoxin produced by Fusarium and Giberella fungal genera, has biological and metabolic effects in various plants. In this study, it was aimed to investigate the protective effect of externally applied FA (0.1 nM) against the damage caused by salt (0.15 M NaCl) stress in onion (Allium cepa L.) plant. Salt stress resulted in an increase in the chromosomal aberrations (CAs) and micronucleus (MN) frequency, a decrease in the mitotic index (MI), fresh weight, root number, germination percentage, and root length. It promoted CAs such as irregular mitosis, bilobulated nuclei, chromosome loss, bridge, unequal seperation of chromosome, vagrant chromosome and polar slip in root meristem cells. In addition, salt stress caused a enhancement in free proline (PR), catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) contents in the roots of onion plant. Moreover, it revealed damage and changes that include the accumulation of some chemical substances such as proline and sugars in epidermis and cortex layer cells, epidermal cell injury, flattening of the cell nucleus, wall thickening in cortex cells, necrotic areas and indistinct transmission tissue in the anatomical structure of onion roots. On the other hand, FA application promoted bulb germination and mitotic activity, strengthened the antioxidant defense system, and reduced chromosome and anatomical structure damages. In conclusion; it has been revealed that exogenous FA application may have a positive effect on increasing the resistance of onion plants to salt stress.

Transcriptomic investigation unveils the role of energy metabolism under low phosphorus and salt combined stress in soybean (Glycine max).

Soybean (Glycine max) is economically significant, but the mechanisms underlying its adaptation to simultaneous low phosphorus and salt stresses are unclear. We employed the Shennong 94-1-8 soybean germplasm to conduct a comprehensive analysis, integrating both physiochemical and transcriptomic approaches, to unravel the response mechanisms of soybean when subjected to simultaneous low phosphorus and salt stresses. Remarkably, the combined stress exhibited the most pronounced impact on the soybean root system, which led to a substantial reduction in total soluble sugar (TSS) and total soluble protein (TSP) within the plants under this treatment. A total of 20,953 differentially expressed genes were identified through pairwise comparisons. Heatmap analysis of genes related to energy metabolism pathways demonstrated a significant down-regulation in expression under salt and low phosphorus + salt treatments, while low phosphorus treatment did not exhibit similar expression trends. Furthermore, the weighted gene co-expression network analysis (WGCNA) indicated that the blue module had a strong positive correlation with TSS and TSP. Notably, 2,3-bisphosphoglycerate-dependent phosphoglycerate mutase 1, FCS-Like Zinc finger 8, auxin response factor 18 isoform X2, and NADP-dependent malic enzyme emerged as hub genes associated with energy metabolism. In summary, our findings indicate that soybean roots are more adversely affected by salt and combined stress than by low phosphorus alone due to reduced activity in energy metabolism-related pathways and hub genes. These results offer novel insights into the adaptive mechanisms of soybeans when facing the combined stress of low phosphorus and salinity.

Potassium-Switch Signaling Pathway Dictates Acute Blood Pressure Response to Dietary Potassium.

BACKGROUND: Potassium (K+)-deficient diets, typical of modern processed foods, increase blood pressure (BP) and NaCl sensitivity. A K+-dependent signaling pathway in the kidney distal convoluted tubule, coined the K+ switch, that couples extracellular K+ sensing to activation of the thiazide-sensitive NaCl cotransporter (NCC) and NaCl retention has been implicated, but causality has not been established. METHODS: To test the hypothesis that small, physiological changes in plasma K+ (PK+) are translated to BP through the switch pathway, a genetic approach was used to activate the downstream switch kinase, SPAK (SPS1-related proline/alanine-rich kinase), within the distal convoluted tubule. The CA-SPAK (constitutively active SPS1-related proline/alanine-rich kinase mice) were compared with control mice over a 4-day PK+ titration (3.8-5.1 mmol) induced by changes in dietary K+. Arterial BP was monitored using radiotelemetry, and renal function measurements, NCC abundance, phosphorylation, and activity were made. RESULTS: As PK+ decreased in control mice, BP progressively increased and became sensitive to dietary NaCl and hydrochlorothiazide, coincident with increased NCC phosphorylation and urinary sodium retention. By contrast, BP in CA-SPAK mice was elevated, resistant to the PK+ titration, and sensitive to hydrochlorothiazide and salt at all PK+ levels, concomitant with sustained and elevated urinary sodium retention and NCC phosphorylation and activity. Thus, genetically locking the switch on drives NaCl sensitivity and prevents the response of BP to potassium. CONCLUSIONS: Low K+, common in modern ultraprocessed diets, presses the K+-switch pathway to turn on NCC activity, increasing sodium retention, BP, and salt sensitivity.

Genome-Wide Identification of LOX Gene Family and Its Expression Analysis under Abiotic Stress in Potato (Solanum tuberosum L.).

The lipoxygenases (LOXs) are non-heme iron-containing dioxygenases that play an important role in plant growth and defense responses. There is scarce knowledge regarding the LOX gene family members and their involvement in biotic and abiotic stresses in potato. In this study, a total of 17 gene family members (StLOXs) in potato were identified and clustered into three subfamilies: 9-LOX type I, 13-LOX type I, and 13-LOX type II, with eleven, one, and five members in each subfamily based on phylogenetic analysis. By exploiting the RNA-seq data in the Potato Genome Sequencing Consortium (PGSC) database, the tissue-specific expressed and stress-responsive StLOX genes in double-monoploid (DM) potato were obtained. Furthermore, six candidate StLOX genes that might participate in drought and salt response were determined via qPCR analysis in tetraploid potato cultivars under NaCl and PEG treatment. Finally, the involvement in salt stress response of two StLOX genes, which were significantly up-regulated in both DM and tetraploid potato under NaCl and PEG treatment, was confirmed via heterologous expression in yeast under salt treatment. Our comprehensive analysis of the StLOX family provides a theoretical basis for the potential biological functions of StLOXs in the adaptation mechanisms of potato to stress conditions.

Integrated ultra-high pressure and salt addition to improve the in vitro digestibility of myofibrillar proteins from scallop mantle (Patinopecten yessoensis).

Myofibrillar protein (MP) is susceptible to the effect of ionic strength and ultra-high pressure (UHP) treatment, respectively. However, the impact of UHP combined with ionic strength on the structure and in vitro digestibility of MP from scallop mantle (Patinopecten yessoensis) is not yet clear. Therefore, it is particularly important to analyze the structural properties and enhance the in vitro digestibility of MP by NaCl and UHP treatment. The findings demonstrated that as ionic strength increased, the α-helix and ß-sheet gradually transformed into ß-turn and random coil. The decrease of endogenous fluorescence intensity indicated the formation of a more stable tertiary structure. Additionally, the exposure of internal sulfhydryl groups increased the amount of total sulfhydryl content, and reactive sulfhydryl groups gradually transformed into disulfide bonds. Moreover, it reduces aggregation through increased solubility, decreased turbidity, particle sizes, and a relatively dense and uniform microstructure. When MP from the scallop mantle was treated with 0.5 mol/L ionic strength and 200 MPa UHP treatment, it had the highest solubility (90.75 ± 0.13%) and the lowest turbidity (0.41 ± 0.03). The scallop mantle MP with NaCl of 0.3 mol/L and UHP treatment had optimal in vitro digestibility (95.14 ± 2.01%). The findings may offer a fresh perspectives for developing functional foods for patients with dyspepsia and a theoretical foundation for the comprehensive utilization of scallop mantle by-products with low concentrations of NaCl.

NaHCO3 loading causes increased arterial pressure and kidney damage in rats with chronic kidney disease.

Sodium bicarbonate (NaHCO3) is commonly utilized as a therapeutic to treat metabolic acidosis in people with chronic kidney disease (CKD). While increased dietary sodium chloride (NaCl) is known to promote volume retention and increase blood pressure, the effects of NaHCO3 loading on blood pressure and volume retention in CKD remain unclear. In the present study, we compared the effects of NaCl and NaHCO3 loading on volume retention, blood pressure, and kidney injury in both 2/3 and 5/6 nephrectomy remnant kidney rats, a well-established rodent model of CKD. We tested the hypothesis that NaCl loading promotes greater volume retention and increases in blood pressure than equimolar NaHCO3. Blood pressure was measured 24 h daily using radio telemetry. NaCl and NaHCO3 were administered in drinking water ad libitum or infused via indwelling catheters. Rats were housed in metabolic cages to determine volume retention. Our data indicate that both NaHCO3 and NaCl promote hypertension and volume retention in remnant kidney rats, with salt-sensitivity increasing with greater renal mass reduction. Importantly, while NaHCO3 intake was less pro-hypertensive than equimolar NaCl intake, NaHCO3 was not benign. NaHCO3 loading significantly elevated blood pressure and promoted volume retention in rats with CKD when compared with control rats receiving tap water. Our findings provide important insight into the effects of sodium loading with NaHCO3 in CKD and indicate that NaHCO3 loading in patients with CKD is unlikely to be benign.

Role of paraoxonase 3 in regulating ENaC-mediated Na+ transport in the distal nephron.

Paraoxonase 3 (PON3) is expressed in the aldosterone-sensitive distal nephron, where filtered Na+ is reabsorbed mainly via the epithelial Na+ channel (ENaC) and Na+ -coupled co-transporters. We previously showed that PON3 negatively regulates ENaC through a chaperone mechanism. The present study aimed to determine the physiological role of PON3 in renal Na+ and K+ homeostasis. Pon3 knockout (KO) mice had higher amiloride-induced natriuresis and lower plasma [K+ ] at baseline. Single channel recordings in split-open tubules showed that the number of active channels per patch was significantly higher in KO mice, resulting in a higher channel activity in the absence of PON3. Although whole kidney abundance of ENaC subunits was not altered in Pon3 KOs, ENaC gamma subunit was more apically distributed within the connecting tubules and cortical collecting ducts of Pon3 KO kidneys. Additionally, small interfering RNA-mediated knockdown of PON3 in cultured mouse cortical collecting duct cells led to an increased surface abundance of ENaC gamma subunit. As a result of lower plasma [K+ ], sodium chloride co-transporter phosphorylation was enhanced in the KO kidneys, a phenotype that was corrected by a high K+ diet. Finally, PON3 expression was upregulated in mouse kidneys under dietary K+ restriction, potentially providing a mechanism to dampen ENaC activity and associated K+ secretion. Taken together, our results show that PON3 has a role in renal Na+ and K+ homeostasis through regulating ENaC functional expression in the distal nephron. KEY POINTS: Paraoxonase 3 (PON3) is expressed in the distal nephron of mouse kidneys and functions as a molecular chaperone to reduce epithelial Na+ channel (ENaC) expression and activity in heterologous expression systems. We examined the physiological role of PON3 in renal Na+ and K+ handling using a Pon3 knockout (KO) mouse model. At baseline, Pon3 KO mice had lower blood [K+ ], more functional ENaC in connecting tubules/cortical collecting ducts, higher amiloride-induced natriuresis, and enhanced sodium chloride co-transporter (NCC) phosphorylation. Upon challenge with a high K+ diet, Pon3 KO mice had normalized blood [K+ ] and -NCC phosphorylation but lower circulating aldosterone levels compared to their littermate controls. Kidney PON3 abundance was altered in mice under dietary K+ loading or K+ restriction, providing a potential mechanism for regulating ENaC functional expression and renal Na+ and K+ homeostasis in the distal nephron.

Biofilm forming, exopolysaccharide producing and halotolerant, bacterial consortium mitigates salinity stress in Triticum aestivum.

Biofilm and EPS characterization of a rhizobacterial isolate BC-II-20 was done using biophysical techniques. SEM revealed surface morphology of EPS powder to be irregular porous web-like structure. FTIR spectra showed peaks of the polymeric carbohydrate functional groups with probable role in imparting biological properties to EPS. XRD analysis showed signal at 220 (2θ) and confirms its amorphous or semi-crystalline nature. EPS derived from bacterial consortium gradually increased under 200 mM, 400 mM, 600 mM and 800 mM NaCl and SEM-EDAX analysis of EPS showed increase in Na & Cl peaks under the above salt concentrations, depicting EPS-NaCl binding. Triticum aestivum plants under 200 mM NaCl stress with different combinations of treatments showed that bacterial consortium provides tolerance. Under 200 mM salt stress the shoot length was 7.74 cm and total chlorophyll was 4.16 mg g-1Fw of the uninoculated plants whereas inoculated ones were 9.94 cm and 5.62 mg g-1Fw respectively. Under salinity stress, membrane stability index was increased from 47 % to 61 % and electrolyte leakage was decreased to 48 % from 64 %, after inoculation with bacterial consortium. Therefore, consortium comprising of these halotolerant and biofilm forming, EPS producing bioinoculants provides salt tolerance and can be exploited as a sustainable alternative for stress tolerance.

Genome-wide analyses of the GbAP2 subfamily reveal the function of GbTOE1a in salt and drought stress tolerance in Ginkgo biloba.

The APETALA2 (AP2) transcription factors play crucial roles in plant growth and stage transition. Ginkgo biloba is an important medicinal plant renowned for the rich flavonoid content in its leaves. In this study, 18 GbAP2s were identified from the G. biloba genome and classified into three clusters. We found that the members of the euAP2 cluster, including four TOEs (GbTOE1a/1b/1c/3), exhibited a higher expression level in most samples compared to other members. Specifically, GbTOE1a may have a positive regulatory role in salt and drought stress responses. The overexpression of GbTOE1a in G. biloba calli resulted in a significant increase in the flavonoid content and upregulation of flavonoid biosynthesis genes, including PAL, 4CL, CHS, F3H, FLSs, F3'Hs, OMT, and DFRs. By contrast, the silencing of GbTOE1a in seedlings decreased the flavonoid content and the expression of flavonoid synthesizing genes. In addition, the silenced seedlings exhibited decreased antioxidant levels and a higher sensitivity to salt and drought treatments, suggesting a crucial role of GbTOE1a in G. biloba salt and drought tolerance. To the best of our knowledge, this was the first investigation into the identification and characterization of GbAP2s in G. biloba. Our results lay a foundation for further research on the regulatory role of the AP2 family in flavonoid synthesis and stress responses.

Integrated transcriptomic and metabolomic analyses elucidate the mechanism of flavonoid biosynthesis in the regulation of mulberry seed germination under salt stress.

Seed propagation is the main method of mulberry expansion in China, an important economic forest species. However, seed germination is the most sensitive stage to various abiotic stresses, especially salinity stress. To reveal the molecular regulatory mechanism of mulberry seed germination under salt stress, flavonoid metabolomics and transcriptomics analyses were performed on mulberry seeds germinated under 50 and 100 mmol/L NaCl stress. Analysis of the flavonoid metabolome revealed that a total of 145 differential flavonoid metabolites (DFMs) were classified into 9 groups, 40 flavonols, 32 flavones, 16 chalcones and 14 flavanones. Among them, 61.4% (89) of the DFMs accumulated continuously with increasing salt concentration, reaching the highest level at a 100 mmol/L salt concentration; these DFMs included quercetin-3-O-glucoside (isoquercitrin), kaempferol (3,5,7,4'-tetrahydroxyflavone), quercetin-7-O-glucoside, taxifolin (dihydroquercetin) and apigenin (4',5,7-trihydroxyflavone), indicating that these flavonoids may be key metabolites involved in the response to salt stress. Transcriptional analysis identified a total of 3055 differentially expressed genes (DEGs), most of which were enriched in flavonoid biosynthesis (ko00941), phenylpropanoid biosynthesis (ko00940) and biosynthesis of secondary metabolites (ko01110). Combined analysis of flavonoid metabolomic and transcriptomic data indicated that phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), chalcone synthase (CHS), flavonol synthase (FLS), bifunctional dihydroflavonol 4-reductase/flavanone 4-reductase (DFR) and anthocyanidin reductase (ANR) were the key genes involved in flavonoid accumulation during mulberry seed germination under 50 and 100 mmol/L NaCl stress. In addition, three transcription factors, MYB, bHLH and NAC, were involved in the regulation of flavonoid accumulation under salt stress. The results of quantitative real-time PCR (qRT‒PCR) validation showed that the expression levels of 11 DEGs, including 7 genes involved in flavonoid biosynthesis, under different salt concentrations were consistent with the transcriptomic data, and parallel reaction monitoring (PRM) results showed that the expression levels of 6 key enzymes (proteins) involved in flavonoid synthesis were consistent with the accumulation of flavonoids. This study provides a new perspective for investigating the regulatory role of flavonoid biosynthesis in the regulation of mulberry seed germination under salt stress at different concentrations.

Assessing the effects of tempol on renal fibrosis, inflammation, and oxidative stress in a high-salt diet combined with 5/6 nephrectomy rat model: utilizing oxidized albumin as a biomarker.

BACKGROUND: Oxidative stress has been implicated in the pathogenesis of chronic kidney disease (CKD), prompting the exploration of antioxidants as a potential therapeutic avenue for mitigating disease progression. This study aims to investigate the beneficial impact of Tempol on the progression of CKD in a rat model utilizing oxidized albumin as a biomarker. METHODS: After four weeks of treatment, metabolic parameters, including body weight, left ventricle residual weight, kidney weight, urine volume, and water and food intake, were measured. Systolic blood pressure, urinary protein, oxidized albumin level, serum creatinine (Scr), blood urea nitrogen (BUN), 8-OHdG, TGF-ß1, and micro-albumin were also assessed. Renal fibrosis was evaluated through histological and biochemical assays. P65-NF-κB was quantified using an immunofluorescence test, while Smad3, P65-NF-κB, and Collagen I were measured using western blot. TNF-α, IL-6, MCP-1, TGF-ß1, Smad3, and P65-NF-κB were analyzed by RT-qPCR. RESULTS: Rats in the high-salt diet group exhibited impaired renal function, characterized by elevated levels of blood urea nitrogen, serum creatinine, 8-OHdG, urine albumin, and tubulointerstitial damage, along with reduced body weight. However, these effects were significantly ameliorated by Tempol administration. In the high-salt diet group, blood pressure, urinary protein, and oxidized albumin levels were notably higher compared to the normal diet group, but Tempol administration in the treatment group reversed these effects. Rats in the high-salt diet group also displayed increased levels of proinflammatory factors (TNF-α, IL-6, MCP1) and profibrotic factors (NF-κB activation, Collagen I), elevated expression of NADPH oxidation-related subunits (P65), and activation of the TGF-ß1/Smad3 signaling pathway. Tempol treatment inhibited NF-κB-mediated inflammation and TGF-ß1/Smad3-induced renal fibrosis signaling pathway activation. CONCLUSION: These findings suggest that Tempol may hold therapeutic potential for preventing and treating rats undergoing 5/6 nephrectomy. Further research is warranted to elucidate the mechanisms underlying Tempol's protective effects and its potential clinical applications. Besides, there is a discernible positive relationship between oxidized albumin and other biomarkers, such as 8-OHG, urinary protein levels, mALB, Scr, BUN, and TGF-ß1 in a High-salt diet combined with 5/6 nephrectomy rat model. These findings suggest the potential utility of oxidized albumin as a sensitive indicator for oxidative stress assessment.